1. Field of the Invention
In general, this particular invention pertains to an apparatus for setting rivets. More specifically, it relates to a novel and improved blind rivet setting tool for setting blind rivet fasteners in material, which tool is extremely simple in construction and highly efficient and reliable in operation.
2. Description of the Prior Art
Blind rivet fasteners for rivetting together various sheets of material have become widely accepted in industry for a variety of reasons. In general, these rivet fasteners are of the type which include a rivet body and a generally elongated rivet mandrel having a head portion. In a typical setting operation therefor, it will be understood that they are inserted into the components to be joined and the mandrel is gripped by a mechanism which is actuated to pull the mandrel axially away from the body. In customary fashion, the axially pulled head upsets the rivet body forming a blind head and the mandrel is eventually ruptured from the upset rivet body. Consequently, a rivet is fastened or set in the material or components to be joined.
Several mechanisms exist which satisfactorily serve the purpose of setting the foregoing types of blind rivets. One conventional category includes hand-held tools. These tools are generally characterized as including two levers or tong arms that are adapted to be pivotally moved towards and away from each other wherein at least one of the arms has associated therewith a conventional chuck assembly arranged to slidably receive and grasp the mandrel in response to movement of the arms. Typically, in response to squeezing the lever or tong arms together, the chuck assembly grips the mandrel and thereafter in further response to movement of the arms together pulls upon the rivet mandrel to set the rivet and rupture the mandrel. The noted hand tool, which is a standard type, performs satisfactorily and has found wide acceptance in the field. Other kinds of rivet setting tools are operated by pneumatic piston-cylinder devices to pivot a lever arm or the like which serves to linearly displace a rod of the standard chuck mechanism to thereby set the rivet. It should be appreciated, however, that whether the above noted type of the blind rivet setting mechanisms are manually operated or pneumatically powered they include the noted jaw chuck mechanism.
The standard chuck mechanism, however, usually includes a threaded nose piece, a collet member, a plurality of gripping jaw members slidably movable within the collet, a spring member for biasing the jaws, and an actuating rod. As is apparent, the conventional rivet setting tools which employ a chuck mechanism having these components are relatively more complicated in construction and costly to produce and assemble than a tool without such components.
There are other known blind rivet setting mechanisms which do not, however, include the above noted type of jaw chuck mechanism. Such types may be generally characterized as including a pair of squeezable tong arms, a manual jaw gripping member which moves relatively to a front section rivet mandrel holder so as to grip a rivet mandrel therebetween. As the tong arms are moved relatively to each other, the jaw member grips the mandrel between it and the mandrel holder and eventually sets the rivet and ruptures the mandrel. Although such devices do not require the use of the noted collet mechanism, they are nevertheless considered relatively complicated in construction and costly to manufacture. These types may be of the category generally described in U.S. Pat. Nos. 3,154,210 and 3,596,496. One significant reason contributing to their complexity is the fact that they require two pivotal axes for successful operation. Beyond such an arrangement resulting in a relatively more complicated construction, it also leads to such hand tools being relatively larger than could otherwise be desirable. Although other known rivet pulling mechanisms are known which employ a single pivotal axis between the two levers and a second pivotal axis for a clamping element and one of the two levers, such as the type being generally described in U.S. Pat. No. 4,027,556, and, preferably, used in application to plastic rivets are limited insofar as many commercially available units would be unsuitable for the typical industrial metal rivet. Moreover, such type suffers from the drawback in that it is constructed such that during a setting operation relatively greater force need be applied by the operator to set the rivet.
Apart from the preceding drawbacks, another disadvantage generally associated with the above category of rivet setting tools is that they may be unsafe to an operator should upon rupturing of the mandrel the latter fly away from the tool and strike the operator.
There are other known categories of hand-operated tools having movable tong arms, such as pliers, electrode pulling tools, brake cable release tools, and the like, which serve to pull upwardly on a wide variety of workpieces in response to a closing element of the arms thereof. Such tools are not, however, specifically designed for, much less capable of setting blind rivet fasteners in work material. In addition, such known hand-operated tools designed for pulling upwardly on a workpiece as a result the lever arms thereof being forced together are rather complicated in construction and otherwise cumbersome in operation.